1. Field of the Invention
The present invention relates to a method of manufacturing a rubber coated fabric for a tire, which can improve the uniformity of a tire.
2. Description of the Related Art
As shown in FIG. 8, a long fabric “d”, in which a tire woven fabric “c”, obtained by tire weaving a warp constituted by a tire cord “a”, with a narrow weft “b” is coated by a rubber, is generally employed in a carcass ply of a pneumatic tire.
At the time of manufacturing the tire, the rubber coated fabric “d” is evenly cut into a plurality of cut pieces “d1” at a desired angle θ (of the order of 75 to 90° in a radial tire) with respect to the tire cord “a”. Thereafter, a ply material “e” is formed by sequentially connecting each of the cut pieces “d1” at the end portions on the non-cut sides. The ply material “e” is then wound around a forming drum and is thereafter expanded in a troidal shape.
At the time of the expansion in the troidal shape, in order to improve the uniformity of the tire, it is necessary to expand in the peripheral direction while maintaining the interval between the tire cords “a” uniform. However, if the weft “b” still intertwines with the tire cord “a”, the uniform expansion is prevented.
In recent years, as disclosed in Japanese Unexamined Patent Publication No. 5-208458, there has been proposed that the weft “b” is previously cut prior to the molding of the tire. In this structure, after the rubber coated fabric is irradiated with an electron beam, as shown in FIG. 9, the rubber coated fabric “d” is passed between a pair of rollers “r1” and “r2” in which peripheral protrusions “f” and peripheral grooves “g” continuously provided in a peripheral direction are alternately formed. Thus, a tensile force is applied to the weft “b” and the weft “b” is cut.
The rubber coated fabric is irradiated for the following reason. If the fabric “d”, coated with rubber, is passed through without irradiating with the electron beam, there is the case where the weft “b” is displaced and thus a sufficient tensile force cannot be applied, due to a soft topping rubber. Therefore, a cut length is widely scattered such that a portion which is not partially cut is generated, and accordingly uniformity cannot be sufficiently improved. On the contrary, in the case where the coated fabric is irradiated, the modulus of the topping rubber is moderately increased by the electron beam, so that it is possible to inhibit the weft “b” from being displaced and thus it is possible to make uniform the cut length of the weft “b”.
However, the structure in which the weft “b” is cut after irradiating with the electron beam tends to become deteriorated in its outer appearance such that a concave-convex trace generated at a time of passing through the rollers remains on the surface of the fabric “d”, whereby a wavy undulation is generated on the side surface of the tire.
As a result, it has been found that a cut length of the weft can be made uniform without irradiating with the electron beam by controlling, in the roller, the width of the peripheral groove, the width of the peripheral protrusion, or the like, within a predetermined range.